add Downloader

Cargo.lock

@@ -1,4 +0,0 @@
-[root]
-name = "plushie-narwhal"
-version = "0.0.1"
-

Cargo.toml

@@ -2,3 +2,6 @@
 name = "plushie-narwhal"
 version = "0.0.1"
 authors = ["A. Malacoda <malacoda@monarch-pass.net>"]
+
+[dependencies]
+reqwest = "0.8.0" 

src/lib.rs

@@ -1,10 +1,12 @@
+extern crate reqwest;
+
 use std::process::Command;
 use std::env;
 
 use std::path::{Path, PathBuf};
 use std::fs::canonicalize;
-use std::fs::File;
-use std::io::Write;
+use std::fs::{File, create_dir_all};
+use std::io::{Write, copy};
 
 pub fn yarn_install () {
     Command::new("yarn").output().expect("failed to execute yarn process");
@@ -137,3 +139,33 @@ pub struct ResourceMount {
     endpoint: &'static str,
     content_type: &'static str
 }
+
+pub struct Downloader {
+    cache: PathBuf
+}
+
+impl Downloader {
+    pub fn new<P: AsRef<Path>>(cache: P) -> Downloader {
+        Downloader {
+            cache: cache.as_ref().to_path_buf()
+        }
+    }
+
+    pub fn get(&self, url: &str) -> PathBuf {
+        if !self.cache.exists() {
+            create_dir_all(self.cache.as_path()).expect("failed to create cache directory");
+        }
+
+        let filename = url.get((url.rfind('/').expect("not a valid url")..)).expect("failed to parse filename");
+        let mut out_path = self.cache.clone();
+        out_path.push(filename);
+
+        if !out_path.exists() {
+            let mut res = reqwest::get(url).expect("failed to download url");
+            let mut file = File::open(out_path.as_path()).expect("failed to open file");
+            copy(&mut res, &mut file).expect("failed to write file");
+        }
+
+        out_path
+    }
+}